Table 1.
Between-site differences in the level of competition between males. Competition was characterized by five distinct parameters: (i) the percentage of females that were guarded at least once among females that moulted as adults; (ii) the percentage of males, among those that were the first to guard any female, that succeeded in guarding their mate until her adult moult, and the remaining males failed due to takeover by rival males; (iii) male turnover, computed as the total number of males that successively guarded each female in the male removal experiment; (iv) the OSR, the daily ratio of adult males to sub-adult females; (v) the tertiary sex ratio, the ratio of males to females that both moulted as adults at each site.
| statistics | ||||||
|---|---|---|---|---|---|---|
| variable | high competition (HC) | low competition (LC) | Χ2 | d.f. | p | |
| (i) | percentage of guarded females (%) | 88.0 | 68.9 | 6.1 | 1 | 0.014 |
| no. of females | 50 | 74 | ||||
| (ii) | success rate of first guarding males (%) | 58.0 | 83.1 | 5.1 | 1 | 0.025 |
| no. of males | 31 | 59 | ||||
| (iii) | male turnover per female | 4 (2–5)a | 1 (1–2) | 9.8 | 1 | 0.002 |
| no. of females | 9 | 15 | ||||
| (iv) | operational sex ratio | 4.42b | 1.13b | 20.3c | 1 | <0.0001 |
| (v) | tertiary sex ratio | 0.50 | 0.25 | 20.9 | 1 | <0.0001 |
| no. of adult moulting | 121 | 189 | ||||
Median value (lower–upper quartiles).
Estimates from the generalized linear model.
Site effect is given after fixing the season effect, as OSR increased throughout the season at both the sites (Χ42=17.60, p=0.0015; site–season interaction, Χ42=4.90, p=0.30).